How much to produce?

If I am in business I need to answer 

the Question: "How much of product X should I produce?"

Answer: Choose Q (quantity) so that Marginal Revenue = Marginal Cost

MR = change in TR/change in Q

TR = p*q

but, that is not the whole answer.

When MR = MC all that means is that is your maximum revenue possibility. 

That does not mean you'll make a DIME.

after choosing Q so that MR=MC determine your profit by the following equation:

Profit = Total Revenue - Total Costs.

When costs < revenue profit is a +

when costs > revenue profit is a -

when costs = revenue profit is a 0

using the ATC (average total costs) formula below, you can compare costs/unit to price/unit at any given point.

Total Cost/Q

if P(per unit) > ATC then profit is a +

if p(per unit) < ATC then profit is a -

if p(per unit) = ATC then profit is a 0